A purified freeze-dried fibronectin concentrate prepared by the Centre National de Transfusion Sanguine from blood donors' plasma pools was tested for safety and effects on recipients' plasma fibronectin levels. The product was administered on 17 occasions to 10 patients with severe sepsis, either as bolus intravenous injection (group B) or as bolus injection of one-half of the dose followed by continuous infusion of the remaining half-dose over a 6-hour period (group B + P). The drug was well tolerated both clinically and biochemically. Following a 1 mg/kg dose of fibronectin, the maximum increase in mean plasma fibronectin levels was 17 +/- 5 mg/l in group B patients and 20 +/- 5 mg/l in group B + P patients. Mean times to peak were 188 +/- 53 min and 282 +/- 106 min respectively in the two groups. A cooperative randomized double-blind trial is currently in progress to evaluate the clinical effectiveness of the product.